In this paper, the theory of materi als with elastic range by Lucchesi and Podio_Guidugli(1988) has been generalized . It has also shown that there are some difficulties on the definition of back s tress as the “cen...In this paper, the theory of materi als with elastic range by Lucchesi and Podio_Guidugli(1988) has been generalized . It has also shown that there are some difficulties on the definition of back s tress as the “center” of the yield surface in the Cauchy space. The back stres s tensor is Lagrangian,and must be defined in the Lagrangian stress space.展开更多
In this paper,such a new lateral displacement function is proposed that the lateral flow velocity is con- tinuous at the entry and the exit of deformation zone.A new kind of finite strip method—the third power B-spli...In this paper,such a new lateral displacement function is proposed that the lateral flow velocity is con- tinuous at the entry and the exit of deformation zone.A new kind of finite strip method—the third power B-spline finite strip method—is put forward to simulate strip rolling process.Front and back tension stresses are formulated.The computed results of the transverse distributions of the front and back tension stresses are close to the experimental results.The paper lays a foundation for further analysing the three-dimensional stresses and deformations of strip rolling.展开更多
We measured serum level of cortisol and lactate, the stiffness of trapezius, skin blood flow and VAS before and after the back massages of 25 senior college students, who had sent stressful days for 11 months starting...We measured serum level of cortisol and lactate, the stiffness of trapezius, skin blood flow and VAS before and after the back massages of 25 senior college students, who had sent stressful days for 11 months starting from April, preparing for the national license examination. These students usually had complaints of stiffness of shoulder and/or lumber. Back massages significantly reduced the level of serum cortisol from 8.85 ± 0.78 to 5.95 ± 0.68 μg/dl, without affecting that of lactate. The treatment also improved the stiffness of the trapezius of students with complaints from 63.24 ± 0.78 to 59.12 ± 0.78 after the treatment without affecting skin blood flow (SKBF). In addition, back massages reduced the VAS value at the same time. These results indicate that back massages of the student are effective to improve the physical and psychological conditions of the students.展开更多
The hot deformation behavior of TI (18W-4Cr-1V) high-speed steel was investigated by means of continuous compression tests performed on Gleeble 1500 thermomechan- ical simulator in a wide range of tempemtures (950℃...The hot deformation behavior of TI (18W-4Cr-1V) high-speed steel was investigated by means of continuous compression tests performed on Gleeble 1500 thermomechan- ical simulator in a wide range of tempemtures (950℃-1150℃) with strain rotes of 0.001s-1-10s-1 and true strains of 0-0. 7. The flow stress at the above hot defor- mation conditions is predicted by using BP artificial neural network. The architecture of network includes there are three input parameters:strain rate,temperature T and true strain , and just one output parameter, the flow stress ,2 hidden layers are adopted, the first hidden layer includes 9 neurons and second 10 negroes. It has been verified that BP artificial neural network with 3-9-10-1 architecture can predict flow stress of high-speed steel during hot deformation very well. Compared with the prediction method of flow stress by using Zaped-Holloman parumeter and hyperbolic sine stress function, the prediction method by using BP artificial neurul network has higher efficiency and accuracy.展开更多
This paper presents two case studies where the rock mass modulus and in situ stress are estimated from the monitoring data obtained during the construction of underground excavations in Sydney,Australia.The case studi...This paper presents two case studies where the rock mass modulus and in situ stress are estimated from the monitoring data obtained during the construction of underground excavations in Sydney,Australia.The case studies comprise the widening of existing twin road tunnels within Hawkesbury sandstone and the excavation of a large cavern within Ashfield shale.While back-analysis from detailed systematic monitoring has been previously published,this paper presents a relatively simple methodology to derive rock mass modulus and in situ stress from the relatively simple displacement data routinely recorded during tunnelling.展开更多
Sleep clearly influences learning and memory since sleep deprivation and stress impairs both cognitive processes. Working memory is an essential cognitive process and refers to a short-term holding of incoming informa...Sleep clearly influences learning and memory since sleep deprivation and stress impairs both cognitive processes. Working memory is an essential cognitive process and refers to a short-term holding of incoming information required to update the long-term mnemonic storage and to manipulate new elements in order to solve problems and make decisions. Nevertheless, the influence of sleep deprivation on working memory has scarcely been studied. In this study we evaluated working memory using the N-back test after increasing periods of wakefulness. Healthy young males were kept awake for 36 hours and the two N-back tasks with low (1-Back) and high (3-Back) levels of complexity were applied every 6 hours. Additionally, salivary cortisol was determined along the study. Unlike the control non-deprived participants, the sleep deprived volunteers showed a significant decrease in their efficiency to solve the 1-Back task after 24 hours of sleep deprivation. However, no differences were observed after 30 and 36 hours of sleep deprivation. Concerning the 3-Back task no differences were observed after sleep deprivation. Regarding reaction time, the deprived group manifested slower responses for the 1-Back task and for the 3-Back task after 30 hours and 36 hours of sleep deprivation, respectively. Cortisol levels presented the normal daily oscillation and no differences were observed between groups. This data suggests that sleep deprivation affects basal states of attention instead of working memory while performing simple tasks. The impact of sleep deprivation on the cognitive performance depends on the moment of day when the task is applied and the complexity of the tests used to assess these mnemonic skills.展开更多
采用Gleeble-3500热物理模拟机对7050铝合金进行等温热压缩实验,获得了合金在变形温度为300~450℃以及应变速率为0.001~1 s^(-1)条件下的应力应变数据。在此基础上,建立了经灰狼优化算法(Grey wolf optimization,GWO)优化的反向传播神...采用Gleeble-3500热物理模拟机对7050铝合金进行等温热压缩实验,获得了合金在变形温度为300~450℃以及应变速率为0.001~1 s^(-1)条件下的应力应变数据。在此基础上,建立了经灰狼优化算法(Grey wolf optimization,GWO)优化的反向传播神经网络(BPNN)、支持向量机(SVR)和随机森林(RF)模型并验证其预测精度。结果表明:经过GWO优化的BPNN、SVR和RF模型预测精度高于原始模型;GWO-BPNN与GWO-RF模型的预测精度比较接近,且均高于GWO-SVR;在外推数据预测上,GWO-BPNN模型的预测精度更高,在内插数据预测上,GWO-RF模型的预测精度更高。不同机器学习模型对流动应力数据的拟合效果不同,其预测精度也存在差异。展开更多
目的:观察消痛方外敷联合健腰活络针法治疗腰椎术后残余腰背痛的临床疗效。方法:将136例腰椎术后残余腰背痛患者按照随机数字表法分为对照组和观察组各68例。对照组给予洛索洛芬钠片治疗,观察组在对照组基础上给予消痛方外敷联合健腰活...目的:观察消痛方外敷联合健腰活络针法治疗腰椎术后残余腰背痛的临床疗效。方法:将136例腰椎术后残余腰背痛患者按照随机数字表法分为对照组和观察组各68例。对照组给予洛索洛芬钠片治疗,观察组在对照组基础上给予消痛方外敷联合健腰活络针法治疗,7 d为1个疗程,连续治疗2个疗程。比较2组治疗前后疼痛视觉模拟评分法(VAS)评分、腰椎Oswestry功能障碍指数(ODI)、腰椎后伸、前屈活动度、氧化应激指标[丙二醛(MDA)、谷胱甘肽过氧化物酶(GSH-PX)、超氧化物歧化酶(SOD)]及血清中疼痛介质[神经生长因子(NGF)、β-内啡肽(β-EP)、P物质(SP)]含量,并比较2组临床总有效率、不良反应发生率、复发率。结果:治疗7 d、14 d 2组VAS评分均逐渐降低(P<0.05),且同一时间点观察组低于对照组(P<0.05)。治疗后,2组腰椎功能ODI指数均降低(P<0.05),且观察组低于对照组(P<0.05)。治疗后,2组腰椎后伸、前屈活动度均增大(P<0.05),且观察组大于对照组(P<0.05)。治疗后,2组血清MDA水平均降低(P<0.05),且观察组低于对照组(P<0.05);2组血清GSH-PX、SOD水平均升高(P<0.05),且观察组高于对照组(P<0.05)。治疗后,2组NGF、SP水平均降低(P<0.05),且观察组低于对照组(P<0.05);2组β-EP水平均升高(P<0.05),且观察组高于对照组(P<0.05)。治疗后,观察组治疗总有效率95.59%,高于对照组85.29%(P<0.05)。2组不良反应发生率比较,差异无统计学意义(P>0.05)。随访3个月,2组复发率比较,差异无统计学意义(P>0.05)。随访6个月,观察组复发率3.08%,低于对照组15.52%(P<0.05)。结论:消痛方外敷联合健腰活络针法治疗腰椎术后残余腰背痛疗效确切,利于缓解痛感,提高腰椎功能,改善腰椎活动度,抗氧化应激损伤,抑制血清中致痛介质表达,且不良反应少,复发率明显降低。展开更多
文摘In this paper, the theory of materi als with elastic range by Lucchesi and Podio_Guidugli(1988) has been generalized . It has also shown that there are some difficulties on the definition of back s tress as the “center” of the yield surface in the Cauchy space. The back stres s tensor is Lagrangian,and must be defined in the Lagrangian stress space.
文摘In this paper,such a new lateral displacement function is proposed that the lateral flow velocity is con- tinuous at the entry and the exit of deformation zone.A new kind of finite strip method—the third power B-spline finite strip method—is put forward to simulate strip rolling process.Front and back tension stresses are formulated.The computed results of the transverse distributions of the front and back tension stresses are close to the experimental results.The paper lays a foundation for further analysing the three-dimensional stresses and deformations of strip rolling.
文摘We measured serum level of cortisol and lactate, the stiffness of trapezius, skin blood flow and VAS before and after the back massages of 25 senior college students, who had sent stressful days for 11 months starting from April, preparing for the national license examination. These students usually had complaints of stiffness of shoulder and/or lumber. Back massages significantly reduced the level of serum cortisol from 8.85 ± 0.78 to 5.95 ± 0.68 μg/dl, without affecting that of lactate. The treatment also improved the stiffness of the trapezius of students with complaints from 63.24 ± 0.78 to 59.12 ± 0.78 after the treatment without affecting skin blood flow (SKBF). In addition, back massages reduced the VAS value at the same time. These results indicate that back massages of the student are effective to improve the physical and psychological conditions of the students.
文摘The hot deformation behavior of TI (18W-4Cr-1V) high-speed steel was investigated by means of continuous compression tests performed on Gleeble 1500 thermomechan- ical simulator in a wide range of tempemtures (950℃-1150℃) with strain rotes of 0.001s-1-10s-1 and true strains of 0-0. 7. The flow stress at the above hot defor- mation conditions is predicted by using BP artificial neural network. The architecture of network includes there are three input parameters:strain rate,temperature T and true strain , and just one output parameter, the flow stress ,2 hidden layers are adopted, the first hidden layer includes 9 neurons and second 10 negroes. It has been verified that BP artificial neural network with 3-9-10-1 architecture can predict flow stress of high-speed steel during hot deformation very well. Compared with the prediction method of flow stress by using Zaped-Holloman parumeter and hyperbolic sine stress function, the prediction method by using BP artificial neurul network has higher efficiency and accuracy.
文摘This paper presents two case studies where the rock mass modulus and in situ stress are estimated from the monitoring data obtained during the construction of underground excavations in Sydney,Australia.The case studies comprise the widening of existing twin road tunnels within Hawkesbury sandstone and the excavation of a large cavern within Ashfield shale.While back-analysis from detailed systematic monitoring has been previously published,this paper presents a relatively simple methodology to derive rock mass modulus and in situ stress from the relatively simple displacement data routinely recorded during tunnelling.
文摘Sleep clearly influences learning and memory since sleep deprivation and stress impairs both cognitive processes. Working memory is an essential cognitive process and refers to a short-term holding of incoming information required to update the long-term mnemonic storage and to manipulate new elements in order to solve problems and make decisions. Nevertheless, the influence of sleep deprivation on working memory has scarcely been studied. In this study we evaluated working memory using the N-back test after increasing periods of wakefulness. Healthy young males were kept awake for 36 hours and the two N-back tasks with low (1-Back) and high (3-Back) levels of complexity were applied every 6 hours. Additionally, salivary cortisol was determined along the study. Unlike the control non-deprived participants, the sleep deprived volunteers showed a significant decrease in their efficiency to solve the 1-Back task after 24 hours of sleep deprivation. However, no differences were observed after 30 and 36 hours of sleep deprivation. Concerning the 3-Back task no differences were observed after sleep deprivation. Regarding reaction time, the deprived group manifested slower responses for the 1-Back task and for the 3-Back task after 30 hours and 36 hours of sleep deprivation, respectively. Cortisol levels presented the normal daily oscillation and no differences were observed between groups. This data suggests that sleep deprivation affects basal states of attention instead of working memory while performing simple tasks. The impact of sleep deprivation on the cognitive performance depends on the moment of day when the task is applied and the complexity of the tests used to assess these mnemonic skills.
文摘采用Gleeble-3500热物理模拟机对7050铝合金进行等温热压缩实验,获得了合金在变形温度为300~450℃以及应变速率为0.001~1 s^(-1)条件下的应力应变数据。在此基础上,建立了经灰狼优化算法(Grey wolf optimization,GWO)优化的反向传播神经网络(BPNN)、支持向量机(SVR)和随机森林(RF)模型并验证其预测精度。结果表明:经过GWO优化的BPNN、SVR和RF模型预测精度高于原始模型;GWO-BPNN与GWO-RF模型的预测精度比较接近,且均高于GWO-SVR;在外推数据预测上,GWO-BPNN模型的预测精度更高,在内插数据预测上,GWO-RF模型的预测精度更高。不同机器学习模型对流动应力数据的拟合效果不同,其预测精度也存在差异。
文摘目的:观察消痛方外敷联合健腰活络针法治疗腰椎术后残余腰背痛的临床疗效。方法:将136例腰椎术后残余腰背痛患者按照随机数字表法分为对照组和观察组各68例。对照组给予洛索洛芬钠片治疗,观察组在对照组基础上给予消痛方外敷联合健腰活络针法治疗,7 d为1个疗程,连续治疗2个疗程。比较2组治疗前后疼痛视觉模拟评分法(VAS)评分、腰椎Oswestry功能障碍指数(ODI)、腰椎后伸、前屈活动度、氧化应激指标[丙二醛(MDA)、谷胱甘肽过氧化物酶(GSH-PX)、超氧化物歧化酶(SOD)]及血清中疼痛介质[神经生长因子(NGF)、β-内啡肽(β-EP)、P物质(SP)]含量,并比较2组临床总有效率、不良反应发生率、复发率。结果:治疗7 d、14 d 2组VAS评分均逐渐降低(P<0.05),且同一时间点观察组低于对照组(P<0.05)。治疗后,2组腰椎功能ODI指数均降低(P<0.05),且观察组低于对照组(P<0.05)。治疗后,2组腰椎后伸、前屈活动度均增大(P<0.05),且观察组大于对照组(P<0.05)。治疗后,2组血清MDA水平均降低(P<0.05),且观察组低于对照组(P<0.05);2组血清GSH-PX、SOD水平均升高(P<0.05),且观察组高于对照组(P<0.05)。治疗后,2组NGF、SP水平均降低(P<0.05),且观察组低于对照组(P<0.05);2组β-EP水平均升高(P<0.05),且观察组高于对照组(P<0.05)。治疗后,观察组治疗总有效率95.59%,高于对照组85.29%(P<0.05)。2组不良反应发生率比较,差异无统计学意义(P>0.05)。随访3个月,2组复发率比较,差异无统计学意义(P>0.05)。随访6个月,观察组复发率3.08%,低于对照组15.52%(P<0.05)。结论:消痛方外敷联合健腰活络针法治疗腰椎术后残余腰背痛疗效确切,利于缓解痛感,提高腰椎功能,改善腰椎活动度,抗氧化应激损伤,抑制血清中致痛介质表达,且不良反应少,复发率明显降低。
